The inventive concepts disclosed herein relate to systems and methods for producing radio-frequency (RF) coverage maps for networks of ground stations. The coverage maps are produced from ground station log files that are generated for a particular network of RF radio stations, including an ARINC VHF Data Link Mode 2 (VDLM2) Network.
Modern commercial and business-type passenger and cargo aircraft are equipped with increasingly sophisticated avionics suites. More and more, data communications between the aircraft and the ground are used to facilitate information exchange with various nodes for administrative flight following, aircraft system monitoring, and alert and warning information which may be of use to the pilots or aircrew in the aircraft, or to the entities exercising administrative or operational control over the aircraft on the ground.
Aircrew have come to expect, and to rely on virtually continuous data stream availability to aid in all phases of aircraft operations as data is exchanged between aircraft and ground stations, in an automated or semi-automated manner. In the aircraft, data is often translated for graphical display on one or more graphical display components as cockpit design is increasingly dedicated to the use of such interactive displays for information display, and many aircraft control and monitoring functions. An objective is to provide the aircrew with easy-to-interpret information at a glance upon which they can make decisions regarding safe and efficient operation of the aircraft while airborne, and modify operations in response to certain unexpected conditions. The particular configuration of the avionics suite in the aircraft will often define the data exchange capabilities for the aircraft.
Various networks exist for data exchange between aircraft and the ground stations that populate the network, providing the data communications coverage for aircraft operating in a particular locale. Among those networks is ARINC's VHF Data Link Mode 2 (VDLM2) Network. As indicated briefly above, data link technology is now a standard in many routine communications between flight crews and air traffic service providers. In addition, flight-operations applications including graphical weather descriptions, electronic charts, and engine/aircraft health monitoring programs are commonly used employing routine data exchange to enhance flight efficiency and safety of flight. The reliance on the routine exchange of information led to an increasingly strong need for greater digital bandwidth from what was historically provided by, for example, character-oriented data network communications available according to the Aircraft Communications Addressing and Reporting System (ACARS®) technology using Minimum Shift Keying (MSK) over carrier transmitted Amplitide Modulation (AM).
VDLM2 was developed and deployed as a bit-oriented, air/ground and ground/ground data link technology to deliver information at a rate of more than ten times the rate used by ACARS®. VDLM2 is able to deliver ACARS® messages using the protocol ACARS over Aviation VHF Link Control (AOA). VDLM2 is based on International Civil Aviation Organization (ICAO) standards and recommended practices (SARPs) and allows for a distributed architecture with future-proof growth potential. VDLM2 is currently the only technology that is compliant with ICAO Aeronautical Telecommunication Network (ATN) requirements for delivering controller-pilot data link communications (CPDLC), also referred to as controller pilot data link (CPDL), which provides a method for air traffic controllers to communicate with aircrew over a datalink system instead of, or in addition to, communications via VHF voice. Among the advantages of VDLM2 is the expanded bandwidth of the system, which supports the provision of an expanded range of flight information, aeronautical operational control, and air traffic control applications and services in data exchange with participating aircraft.
Each VDLM2 installation consists of a number of ground stations that are particularly placed, often in the vicinity of airports to attempt to ensure continuous communication between aircraft and the data network. Simulations are employed to provide a basic local architecture for initial positioning of a particular number of ground stations at a specified location. An evaluation maybe undertaken to determine an initial ground station system laydown to provide reasonable communication coverages as the aircraft flies in a vicinity of a particular location in order that an assessment can be made as to whether VHF communication services are ubiquitously available to a particular aircraft in the vicinity of the particular location. A shortfall in the employment of simulations is that they may not account for certain operational issues (including multipath issues) and certain physical limitations including, but not limited to, undocumented obstructions. In this latter category, for example, airports change as construction on, or in a vicinity of, an airport facility emplaces unforeseen obstructions to continuous network communication coverage.
Simulations have previously been used to estimate a coverage area surrounding a particular station. Simulations are, however, only as good as the inputs provided. In this regard, a particular simulation may provide a picture of what an expected area of RF coverage looks like. Ground stations are then deployed typically on, or in a vicinity of, a particular airport according to such expected areas of RF coverage. The airport is populated with a number of ground stations until an estimate is made, based on the simulation, that full area coverage in a vicinity of the airport has been achieved.
The above conventional scheme provides some manner of a planning tool but does not supplant a need for some manner of collection of actual measurements in order to determine an area of coverage in the vicinity of a particular station.
It has been extremely difficult to characterize the actual performance of VDLM2 ground stations, to establish the RF coverage area of a ground station, and to validate the RF predicted coverage produced from simulations. To date, the most common method used to collect coverage and performance data is to instrument avionics hardware on a particularly outfitted aircraft and to collect logs from either dedicated or revenue flights. There are substantial drawbacks associated with this method of coverage verification in that certification issues abound, access to such dedicated assets is very limited, and the dedicated flight time is expensive and requires extensive planning.
It is not considered acceptable to simply wait for aircrew complaints and the attendant disruptions of operations and observations regarding the lack of appropriate customer service by the network provider.